#241 - Document IGX Thor hybrid-GPU and ibdev2netdev gaps

[RamyaGuru]

Closes Issue #241

Running the raw GPUDirect sweep on an IGX Thor devkit surfaced three places where the system tuning tutorial is wrong or silently unhelpful on a host that pairs the Thor iGPU with a discrete card.

Generalize the "IGX Orin" tab to "IGX Series" and name both tested configurations: Orin with an RTX 6000 Ada on IGX SW 1.1, and the Thor devkit with an RTX PRO 6000 on Ubuntu 24.04 / driver 580. Everything in the tab applies to both; the only divergence is GPU selection, so it is stated once rather than repeated per step.

That divergence, verified on the Thor rig:

• CUDA enumerates the two GPUs in the opposite order from nvidia-smi/NVML. CUDA_VISIBLE_DEVICES=0 resolves to the discrete RTX PRO 6000 while nvidia-smi calls it index 1, so numeric selection silently targets the wrong device in either direction. UUID is the only reliable form.
• The Tegra CUDA driver initializes one GPU class per process. CUDA_VISIBLE_DEVICES=0,1 fails in cuInit rather than returning two devices.
• With no explicit selection CUDA resolves to the iGPU, so is_any_integrated_gpu() returns true and tune_system.py skips or downgrades four checks -- peermem, gpudirect, topo, bar1-size -- none of which ever look at the discrete card. Prefixing the run with the discrete GPU's UUID restores them.

For containers, --privileged populates /dev with the Tegra iGPU nodes and the runtime's device selection stops working: --gpus '"device=N"' and NVIDIA_VISIBLE_DEVICES=GPU- both leave CUDA seeing only the iGPU. -e CUDA_VISIBLE_DEVICES=GPU- does work, and the selected GPU becomes CUDA ordinal 0, so memory_regions[*].affinity must be 0 regardless of what nvidia-smi reports. Documented against the raw benchmarking container recipe, including the two forms that do not work, so they are not retried.

ibdev2netdev is not in Ubuntu's infiniband-diags; it ships in mlnx-tools from the DOCA-Host repository. On a host without that repository the package installs cleanly and the tool is still missing, which is how the MRRS/MPS/MTU checks came to be bypassed with only a warning that recommended the package that had already been installed. Correct the install list and the three tune_system.py messages, and add a sysfs fallback for the IB-device to netdev to PCIe mapping that needs no Mellanox tooling.

Also rename the platform-tab key igx-orin to igx-series in the TOC javascript and stylesheet. The key is positional, not derived from the label, so this is cosmetic.

No logic changes in tune_system.py; the guidance strings only. The per-GPU gating fix for check_bar1_size and check_gpu_nic_topology, which short-circuit on is_any_integrated_gpu() instead of iterating devices the way check_gpudirect_support already does, is left for a follow-up issue.

Assisted-by: Claude

[greptile-apps]

Greptile Summary

This PR expands the IGX system-configuration guidance to cover hybrid-GPU IGX Thor hosts and corrects the documented source of ibdev2netdev.

• Documents UUID-based GPU selection and CUDA ordinal handling for host and privileged-container workflows.
• Adds a sysfs fallback for InfiniBand-device, netdev, and PCIe mapping.
• Updates tune_system.py diagnostics to identify the correct packages and repositories.
• Renames the IGX platform-tab key and label consistently from Orin-specific to IGX Series.

Confidence Score: 5/5

The PR appears safe to merge, with the documentation, diagnostic messages, and platform-tab assets remaining internally consistent.

No concrete changed-code-triggered runtime, documentation workflow, security, or repository-rule failure remains after checking the package guidance, GPU affinity semantics, tab-key consumers, commit metadata, and whitespace.

Important Files Changed

Filename	Overview
docs/tutorials/system_configuration.md	Broadens the IGX tutorial to Thor, adds hybrid-GPU selection guidance, corrects package installation information, and provides a tooling-independent sysfs mapping fallback.
docs/benchmarks/raw_benchmarking.md	Documents the verified privileged-container invocation and CUDA ordinal requirements for hybrid IGX Thor systems.
python/tune_system.py	Changes only diagnostic strings so missing ibdev2netdev and setpci messages identify their actual package sources.
docs/javascripts/platform-tab-toc.js	Renames the positional IGX tab key consistently with the updated tutorial label and stylesheet selectors.
docs/stylesheets/extra.css	Updates platform-specific TOC filtering selectors to consume the renamed IGX tab key.

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